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You may want to wait to get a booster shot

After a long and tense meeting today, an FDA committee has unanimously recommended that the agency approve third injections of the Pfizer COVID-19 vaccine for Americans who are over age 65 or at high risk for severe COVID-19. The vote came after the panel voted overwhelmingly against the original question: allowing boosters for anyone over the age of 16. If the FDA follows the committee’s recommendation (as expected), a CDC committee next week will help refine those guidelines and clarify which groups qualify as “high risk.”

Even as we await these final decisions, the summer wave of COVID infections in the country seems to be passing. Cases and hospital admissions show a slightly decreasing trend. Now that we have more clarity about or (and ThatAmericans need booster shots — and since so many people are already getting boosters, a hell of a lot more questions arise: When, exactly, should those people get those photos? Is it better to load up extra antibodies as soon as possible, or should people wait for COVID rates to start rising again?

Here’s an easy starting point: If you’re already eligible for a third shot because you’re immunocompromised, make sure to get your turn early. The CDC recommends wait at least 28 days after your second mRNA dose, while two experts told me the best period is four to five months later. In many immunocompromised people, the first one or two injections may not have caused a strong enough response in the body to provide lasting protection. For them, the booster shot isn’t meant to fill the cracks of your shield against the virus; it’s primarily for making that shield.

Things get squisier for vaccinated people with relatively healthy immune systems. They will already be on par with newly minted B and T cells, waiting to produce antibodies and attack the coronavirus. Ali Ellebedy, an immunologist at Washington University in St. Louis, told me that the longer those cells mature in the body, the better prepared they are to fight off the invader. If delivered too early, a new dose of the vaccine could cause “something that already worked to restart,” he said. Ellebedy recommended that you delay any booster injections for at least six months after your first course of vaccination. Eight months is better; even a year would be good.

At the same time, booster shots increase the measurable level of antibodies in the blood, pretty much when they are received. The clinical benefits of this spike for fully vaccinated people remain unclear, although there is preliminary evidence that an increase in antibodies could reduce your chances of getting sick, or of transmitting the Delta variant to other people — at least until you do. antibody levels decrease.

Most people’s antibody levels peak a few weeks after their first COVID vaccine shots. If the same goes for boosters, you might be tempted to time your next shot three weeks before wanting to be most protected. Perhaps the virus emerged in your county last December and you fear it will do the same this year – so you decide to get your booster around Veterans Day. You may want to make sure your Uncle Dave doesn’t get infected over Thanksgiving, so make an appointment for Halloween.

The problem is that “a few weeks” is just an average. Müge Çevik, a virologist at the University of St Andrews, told me that different people develop antibodies at very different rates. In general, the immune system of young, healthy people works quickly and can reach their maximum antibody levels in just seven days. Older people, or those with compromised immune systems, can take weeks longer. Since we don’t know how long those peaks last, these differences could be crucial.

To predict when you’ll be most at risk, you also need to predict when the transmission in your community will be the highest, which is nearly impossible to do with any precision. “It’s very likely that we’ll see another wave this winter,” Saskia Popescu, an infectious disease epidemiologist at George Mason University, told me, but it’s not feasible to identify the specific week or month when the cases are on any given day. particular place will peak. . (Even a winter wave isn’t certain: “Right now, we don’t really have a consistent seasonal pattern,” because all of our peaks have been shaped by behaviors like masking and distancing, Çevik said.) Popescu, too, pointed out that the rise of home testing and the decline of mass test sites could make it more difficult to detect smaller uplift ticks until a wave is fully headed toward us.

Still, the mere probability of a winter surge makes it reasonable to wait, at least a little. Çevik worries that if a large number of people rush to get their extra injections, their antibodies will have faded by the time they are most needed, and a winter wave could cause even more breakthrough infections. Çevik advised her own parents, whom she described as “in clinically vulnerable groups,” to get their boosters in late September or October. Young people with a healthy immune system can wait until November or early December. (This advice comes with exceptions: For example, if you’re a nurse on a COVID ward in a province where cases are on the rise, it might be wise to get a booster now.)

Ultimately, the dynamics of transmission in your area may be more important than the details of your personal vaccination schedule. David Dowdy, an epidemiologist at the Johns Hopkins Bloomberg School of Public Health, would prefer boosters to be distributed sparingly and strategically to communities showing signs of an approaching wave. While everyone else waits, vaccine makers can update their formulas to better protect them from Delta and set up randomized controlled trials to collect better data on how their original doses and boosters are performing.

On an individual level, Dowdy told me, if eligible people get a third shot now, there’s probably minimal harm. But vaccine makers could have another shot in a few months, designed around circulating variants, or even an intranasal option that could stop infections sooner. Once the government announces that tens of millions of people should get a booster now, it could be hard to convince them again in a few months, when a better option is available. And those who decide to get a booster now may find themselves ineligible for a fourth shot when that better option comes along. The number of cases may seem scary now, but this pandemic has proven time and again that it can certainly get worse. “I think it’s important not just to say: Should I get a booster or not?‘ Dowdy said, ‘But rather, Would you rather have a booster now or save the chance for later?

This article previously misrepresented that the CDC recommends that immunocompromised Americans receive a booster shot at least 28 days after an initial Johnson & Johnson dose. In fact, the CDC does not currently recommend booster shots for people vaccinated with Johnson & Johnson.